A vector network analyzer (VNA) is a useful instrument for many applications where electrical and/or microwave measurements, such as transmission and reflection properties, are needed. VNA's are usually used where the electrical signals have a high frequency, ranging from (but not limited to) 10 kHz to 100 GHz. Since a VNA can be used to measure complex impedances of circuits at high frequencies, VNAs can be found in many electronic and radio frequency (RF) laboratories, as well as in chip/microwave device or system manufacturing facilities.
A VNA can apply a stimulus sine wave to a device under test (DUT) and perform a series of measurements and calculations. VNAs are often used to characterize two-port networks such as amplifiers and filters, but they can be used on networks with an arbitrary number of ports. A two-port VNA can measure both reflected signals from the DUT and transmitted signals through the DUT. Additionally, the VNA can calculate S-parameters and other related parameters for that DUT. The VNA can repeat this procedure using different frequencies and/or power levels to measure the desired characteristics of the DUT.
The basic architecture of the VNA includes a signal generator, a test set, one or more receivers and a display. A traditional VNA test set 100, as shown in FIG. 1, may include four ports (110, 120, 130 and 140) which may be connected, for example to the DUT ports 150. Each of the test unit ports may be connected to a source transmitter and requires two directional couplers which are connected to two receivers for measuring the reference signal (i.e. R1, R2, R3 and R4) and the received signals (i.e. A, B, C and D). Therefore, according to the prior art solution two receivers are required for each test port. The traditional VNA further includes a number of switches and couplers, such as couplers 115,117,125,127, 135, 137, 145 and 147 located on each branch of the VNA test set 100. The couplers are configured to sample, measure and direct the transmit signal (forward) and the return signals (backward direction) at the VNA (for each direction a single coupler is needed).
The receivers and the transmitters at the VNA are synchronized according to methods known in the field. The testing may be performed simultaneously on all the VNA's ports or separately and alternately at each port.
As illustrated in FIG. 1 the traditional VNA is a complex device which typically occupies a large space, includes multiple elements (such as switching elements connectors and couplers) and is expensive. Moreover, some of the elements are mechanical elements (i.e. coaxial switches) that must be frequently switched, resulting in the decrease of the traditional VNA's reliability. There is a need for an improved, cheap, compact and reliable VNA.